Split bills by income
When one of you earns more, splitting rent down the middle takes a bigger bite out of the smaller salary. Proportional splitting fixes that: you each pay the same share of what you earn, not the same number of dollars.
Calculator
Each month
Fill in a bill and both incomes to see the split.
How proportional splitting works
Add both incomes together, then work out what fraction each person contributes. That fraction is the share of every shared bill they pay.
On $95,000 and $60,000, the total is $155,000. The higher earner brings in about 61% of it, so they pay about 61% of the rent. Both people end up with roughly the same proportion of their income left over — which is the thing a 50/50 split gets wrong when salaries differ.
Gross or take-home?
Take-home pay is usually the better basis. It's the money that actually reaches the bills, and it accounts for the two of you being taxed differently — which gross income can hide. The calculator doesn't care which you use, as long as you use the same one for both people.
Is proportional actually fairer?
It depends what you're measuring. A 50/50 split is equal in dollars. A proportional split is equal in effort. Neither is automatically right, and plenty of couples split evenly on principle and are happy with it.
What tends to matter more than the ratio is that you both picked it on purpose, and that neither of you has to keep re-doing the arithmetic every month.
The hard part isn't the maths
It's the following month, and the one after: who paid what, who's owed, and neither of you wanting to be the one keeping score. Isomoira applies whatever ratio you agreed to every shared expense automatically, keeps one running balance, and never sends either of you a notification about money.